;(function(window, undefined){

    "use strict";

    // Helper functions.
    var getContext = function(width, height){
        var canvas = document.createElement("canvas");
        canvas.setAttribute('width', width);
        canvas.setAttribute('height', height);
        return canvas.getContext('2d');
    };

    var getImageData = function(img, loaded){

        var imgObj = new Image();
        var imgSrc = img;

        // Can't set cross origin to be anonymous for data url's
        // https://github.com/mrdoob/three.js/issues/1305
        if ( imgSrc.substring(0,5) !== 'data:' )
            imgObj.crossOrigin = "Anonymous";

        imgObj.onload = function(){
            var context = getContext(imgObj.width, imgObj.height);
            context.drawImage(imgObj, 0, 0);

            var imageData = context.getImageData(0, 0, imgObj.width, imgObj.height);
            loaded && loaded(imageData.data);
        };

        imgObj.src = imgSrc;

    };

    var makeRGB = function(name){
        return ['rgb(', name, ')'].join('');
    };

    var mapPalette = function(palette){
        var arr = [];
        for (var prop in palette) { arr.push( frmtPobj(prop, palette[prop]) ) };
        arr.sort(function(a, b) { return (b.count - a.count) });
        return arr;
    };

    var fitPalette = function(arr, fitSize) {
        if (arr.length > fitSize ) {
            return arr.slice(0,fitSize);
        } else {
            for (var i = arr.length-1 ; i < fitSize-1; i++) { arr.push( frmtPobj('0,0,0', 0) ) };
            return arr;
        };
    };

    var frmtPobj = function(a,b){
        return {name: makeRGB(a), count: b};
    }


    // RGBaster Object
    // ---------------
    //
    var PALETTESIZE = 10;

    var RGBaster = {};

    RGBaster.colors = function(img, opts){

        opts = opts || {};
        var exclude = opts.exclude || [ ], // for example, to exclude white and black:  [ '0,0,0', '255,255,255' ]
            paletteSize = opts.paletteSize || PALETTESIZE;

        getImageData(img, function(data){

            var colorCounts   = {},
                rgbString     = '',
                rgb           = [],
                colors        = {
                    dominant: { name: '', count: 0 },
                    palette:  []
                };

            var i = 0;
            for (; i < data.length; i += 4) {
                rgb[0] = data[i];
                rgb[1] = data[i+1];
                rgb[2] = data[i+2];
                rgbString = rgb.join(",");

                // skip undefined data and transparent pixels
                if (rgb.indexOf(undefined) !== -1  || data[i + 3] === 0) {
                    continue;
                }

                // Ignore those colors in the exclude list.
                if ( exclude.indexOf( makeRGB(rgbString) ) === -1 ) {
                    if ( rgbString in colorCounts ) {
                        colorCounts[rgbString] = colorCounts[rgbString] + 1;
                    }
                    else{
                        colorCounts[rgbString] = 1;
                    }
                }

            }

            if ( opts.success ) {
                var palette = fitPalette( mapPalette(colorCounts), paletteSize+1 );
                opts.success({
                    dominant: palette[0].name,
                    secondary: palette[1].name,
                    palette:  palette.map(function(c){ return c.name; }).slice(1)
                });
            }
        });
    };

    window.RGBaster = window.RGBaster || RGBaster;

})(window);